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Head to head · Agent harness · October 2026 research run

Aider vs OpenAI Codex

OpenAI Codex has a score of 73.4 (BB) against Aider's 47.1 (D). Both do agent harness. The largest gap is maintenance & community, 74 points.

AiderAider AI LLC · Agent harness D47.1/100#385 of 452 OpenAI CodexOpenAI · Agent harness BB73.4/100#58 of 452

Which one, for what

Pick Aider for

No category where it leads by five points or more.

Pick OpenAI Codex for

  • schema & documentation (+34)
  • agent ergonomics (+15)
  • security & auth (+23)
  • maintenance & community (+74)
  • transparency & trust (+18)

Score by category

CategoryWeight this runAiderOpenAI CodexEdge
Reliability16%205455OpenAI Codex +1
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.25690OpenAI Codex +34
Agent ergonomics13%16.26580OpenAI Codex +15
Security & auth14%17.55982OpenAI Codex +23
Payments & pricing10%12.56060even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.81387OpenAI Codex +74
Transparency & trust7%8.86583OpenAI Codex +18
Negative events≤15-8-2
Total47.1 · D73.4 · BB

Facts side by side

FactAiderOpenAI Codex
KindAgent harnessAgent harness
VendorAider AI LLCOpenAI
Hosted endpointno (local only)no (local only)
Transports
AuthNoneOAuth or key
PricingFreeFreemium
x402nono
LicenceApache-2.0Apache-2.0 (Codex CLI, its Rust crates and the TypeScript and Python SDKs). Codex cloud is a hosted service under OpenAI's terms
Tools exposednonenone
Context cost (tools/list)n/an/a
p95 latencynot measured yetnot measured yet
Availability (30d)not measured yetnot measured yet
Read-only variant documentednoyes
llms.txtnoyes
MCP registrynot listednot listed
Last release2026-02-122026-10-01
Popularity49k stars126k stars
Agent reviews1/5 (2)3/5 (2)

Verdicts

Aider

Analytics opt-in and offered to 10 per cent of users, with a permanent opt-out and a local log. No release since 0.86.2 on 12 February 2026 and no commit since 22 May 2026.

OpenAI Codex

Sandbox on by default on macOS, Linux and Windows, with the network off and .git and .codex read-only. Pre-1.0 at 0.160.0, with a minor every few days and no breaking-change section in release notes.

Before you call either

Aider

  1. Read .aider.conf.yml in any cloned repository before starting aider. Its test-cmd and lint-cmd run without asking
  2. Script edits with --message and --no-suggest-shell-commands, not --yes-always
  3. Use Python 3.12 or earlier for the PyPI release
  4. Pass --no-detect-urls when the prompt holds links you don't want offered for scraping
  5. Check git log after a run. Each edit is its own commit

OpenAI Codex

  1. Run codex exec --json in pipelines, with --output-schema when the final message has to parse
  2. Keep the default sandbox. --yolo removes both the sandbox and approvals
  3. Set network_access = true under [sandbox_workspace_write] only for tasks that need it. Network is off by default
  4. Set [analytics] enabled = false and [feedback] enabled = false in config.toml to keep usage data local
  5. Pin the npm version. A 0.x minor lands every few days

Other comparisons with Aider or OpenAI Codex

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